Anaplasma marginale major surface protein 3 is encoded by a polymorphic, multigene family

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Published on: July 5, 2019

A R Alleman1, G H Palmer, T C McGuire

  • 1Department of Physiological Sciences, University of Florida, Gainesville 32610, USA. ARALL@GNV.IFAS.UFL.EDU

Infection and Immunity
|January 1, 1997
PubMed

Insights

Anaplasma marginale uses a polymorphic multigene family to vary its surface protein MSP3, contributing to antigenic variation. This genetic diversity may explain persistent infections in cattle.

Area of Science:

  • Veterinary Microbiology
  • Molecular Biology
  • Immunology

Background:

  • Anaplasma marginale, a significant cattle pathogen, exhibits antigenic variation in its surface proteins.
  • The immunodominant surface protein, MSP3, shows considerable structural and antigenic polymorphism across different strains.

Purpose of the Study:

  • To investigate the genetic basis of MSP3 polymorphism in Anaplasma marginale.
  • To determine if multigene families contribute to the antigenic variation of MSP3.

Main Methods:

  • Cloning and expression of the A. marginale msp3-12 gene in Escherichia coli.
  • Using msp3-12 as a probe to identify homologous gene copies in A. marginale genomes.
  • Sequence analysis of identified msp3 gene variants.

Main Results:

  • Multiple, partially homologous msp3 gene copies were detected in the genomes of three A. marginale strains.
  • These msp3 gene copies were distributed throughout the bacterial chromosome.
  • Sequence analysis revealed conserved and variant regions within msp3 genes, with some amino acid blocks related to MSP2.

Conclusions:

  • A polymorphic multigene family is at least partially responsible for the variation in Anaplasma marginale's MSP3 protein.
  • Multigene families are likely employed by A. marginale to vary key antigenic surface proteins.
  • These findings offer insights into the antigenic variation mechanisms driving persistent infections in carrier cattle.

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